Like you say The text may be from Miriam or from Danielle after take the picture
Probably Miriam given 720.
Yeah, that was my thought too. We know Miriam sent a text to Adrian in #720. There's no evidence of anyone else sending him a text in that time period. In #726 he's obviously replying to a text. Everything point to Miriam; nothing points to anyone else.
Part of me wonders if Evil!Adrian programmed Miriam to do serial recruiting on his behalf, but I don't think he would have any way of knowing about whatever mystical power she's been using on Heidi.